DPP4 inhibitors, also known as “gliptins”, have been added to treatment regimens of type 2 diabetes, as they strongly reduce DPP4-mediated inactivation of the incretin hormones glucagon like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) and thus lower blood glucose levels. Here, GCG is linked to type 2 diabetes mellitus.